(308f) Detection of Biomarkers for Different Diseases On Biosensor Surfaces

A fractal analysis is used to analyse the binding and dissociation (if applicable) kinetics of biomarkers to different biosensor surfaces. The dual-fractal analysis is used only if the single-fractal analysis does not provide an adequate fit.

For the binding and dissociation of IFN-gamma in solution to the aptamer modification (Tuleouva et al,. 2010), and for a single-fractal analysis, the (a) binding rate coefficient, k exhibits close to a third (equal to 3.01) order of dependence on the fractal dimension or the degree of heterogeneity that exists on the biosensor surface, and (b) the affinity, K (k/k_d) exhibits close to a fifth (equal to 5.064) order of dependence on the ratio of fractal dimensions, D_f/D_fd. This indicates that both the binding rate coefficient, k and the affinity, K are very sensitive to the nature or the degree of heterogeneity that exists on the biosensor surface.

For the binding of different concentrations of CA-II anhydrase in solution the binding of rate coefficient, k exhibits a mild (equal to 0.435) order of dependence on the CA-II anhydrase concentration in solution, (a) the binding rate coefficient, k exhibits close to a second (equal to 2.011) order of dependence on the fractal dimension, D_f that exists on the biosensor surface, and (b) the ratio of the binding rate coefficients, k₂/k₁ exhibits higher than a third (equal to 3.386) order of dependence on the ratio of fractal dimensions, D_f2/D_f1.

The above relationships presented are typical of the ones presented for the biomarkers for the other diseases analysed and for this presentation. They provided a means by which these rate coefficients or affinities may be manipulated in desired directions in order to improve the different biosensor performance parameters.